Bike
but not by much.
Most cossie 'races' with bikers have the element of surprise, where the biker thinks WTF?! then has to drop down a gear or 3. But your mate will be ringing its neck from the off and will be tough to catch and tougher to overtake.
In the bends, you'll kill him.... literally
Interested in the result tho'... good luck with the new engine.
Newts